This invention relates to a communications system for classifying and forwarding packets for transmission over a digital communication channel.
With the evolution of communication services toward a greater penetration of packet transmission, a packet network may need to support a plurality of applications for voice services and video services. However, different types of services have different requirements in order to achieve the objectives of quality of service (QoS). Time latency and packet error rate (PER) are often used to describe the QoS objectives. Voice services typically require a small time latency (which is associated with the delay of the voice signal). On the other hand, entertainment broadcast video typically requires a small packet error rate but does not require a small time latency. Moreover, the processing required for providing a small packet error rate often entails substantial error correcting processing when the signal is transmitted over an imperfect communication channel. If a packet network serves entertainment broadcast video, one would configure the packet network to have a large degree of error correcting capability in order to guarantee a small packet error rate at the expense of a greater time latency. However, this policy may not provide satisfactory support for voice service if the same packet network is concurrently serving applications for voice services.
With the prior art, a single forward error correction (FEC) path is often chosen that is a compromise between a reasonable packet error rate and a reasonable delay; however, this approach is not an optimal solution because either there is more delay for voice signals than desired or a higher packet error rate than is desirable for video services. Another conventional approach is to utilize more one than one forward error correction path; however, only one FEC path can be used at a given time. In other words, FEC paths cannot be used concurrently. However, a packet switch may serve different types of services at a given time.
There is a need for a packet network to have the capability of selecting the FEC path that best meets the QoS objectives for applications supporting different services such as video services and voice services.
The present invention provides a method and apparatus for a communications system that classifies packets that are transmitted over a digital communication channel with at least one error-correcting transmission path. Quality of Service (QoS) objectives are used to select the appropriate transmission path that satisfies the relevant metrics of service quality such as packet latency, variance of the packet latency, information throughput, and packet error rate (PER). One transmission path supports forward error correction with an associated amount of time latency that is consistent with the QoS objectives of an originating application. The communications system manages, monitors, and prioritizes packets and allocates bandwidth with a packet network in order to satisfy the QoS objectives associated with the originating application. The communications system configures the transmission path according to QoS objectives and bandwidth requirements and selects a transmission path that is associated with QoS objectives best matched to the QoS objectives as required by the originating application. The processing of the packet optionally includes scrambling and interleaving of the packet. A packet can be reclassified with respect to QoS and bandwidth requirements in order to adjust the policy-based communications system to varying service demands. Alternatively, available bandwidth can be re-allocated among the plurality of transmission paths. The receiver, in accordance with the present invention, utilizes corresponding inverse functions to deliver packets to the terminating application.